Synthesis of Pyrazines and Quinoxalines via Acceptorless Dehydrogenative Coupling Routes Catalyzed by Manganese Pincer Complexes

Base-metal
catalyzed dehydrogenative self-coupling of 2-amino alcohols
to selectively form functionalized 2,5-substituted pyrazine derivatives
is presented. Also, 2-substituted quinoxaline derivatives are synthesized
by dehydrogenative coupling of 1,2-diaminobenzene and 1,2-diols. In
both cases, water and hydrogen gas are formed as the sole byproducts.
The reactions are catalyzed by acridine-based pincer complexes of
earth-abundant manganese.